It has become important that various types of electric power equipment be interconnected with microgrids (small-scale electric power systems) and used. However, in order that power supply equipment utilizing natural energies such as solar generators and wind power generators be interconnected and used, it is necessary to perform such control that the total electric power obtained by adding output power generated by natural energies to output powers of other power supply equipment such as diesel generators (hereinafter referred to as DEGs), gas turbine generators, and storage batteries is coincident with the total amount of load obtained by summing up the demands of the supply destinations (i.e., the amounts of load on power generators). Therefore, the output of power generators is conversely increased in conformity either with a decrease in the output of natural energies or with a load increase or decrease.
In order to increase the output of power generators in preparation for decreases in output of natural energies or sudden increases in load in this way, it is necessary to previously activate power generators. However, if the number of operating power generators is increased, fuel for idling operation of the power generators is needed. This impairs the economy. Furthermore, if power generators such as DEGs are run at low loads while throttling down their outputs over long times, the combustion temperature of fuel within the engines drops. Combustion residue components of fuel (components causing black smoke of gas emissions) are accumulated, thus deteriorating the environment-friendliness. Accordingly, such control must be performed that an appropriate number of power generators are run and the total output power generated is brought into coincidence with the total demand while stopping other power generators. Such control is called microgrid control.
In the technique set forth in patent literature 1, control is provided such that the total electric output generated is brought into coincidence with the total electric power demand by shortening the periods of outputs of natural energies and the periods of forecasting of load so as to perform accurate forecasts while stopping unnecessary power generators.
Electric power equipment referred to herein includes solar power generators, wind power generators, diesel generators, gas turbine power generators, brackish water desalination power generators, other power generators, production facilities equipped with power generators employing electric power as motive power (such as refrigerators and push benches), electric vehicles, charging facilities for electric vehicles, and storage batteries for performing charging and discharging with electric power. Unless otherwise specifically stated, power supply facilities indicate the above-described power generators and secondary batteries such as storage batteries. Load facilities indicate the above-described production facilities and charging facilities.